There EMC electromagnetic compatibility (Electromagnetic compatibility) is a requirement that must be met by many products whose sale is subject to specific regulations depending on the target market. It is by affixing the CE marking on electrical products sold in the European Union, but also for vehicle approval. The greater the number of control units and electronic components, the more critical the assessment of the tests by the Manufacturer. This is the reason that has made the electromagnetic compatibility of new cars one of the main mandatory tests for vehicle type approval in the European Union. How is the electromagnetic compatibility of cars tested? We talk about it with Eng. Pietro Vergani, Business Unit Manager Commercial Product TÜV Italywho explained to us the operation of the EMC laboratory of the TÜV Italia Center in Volpiano.

WHAT ARE CAR ELECTROMAGNETIC COMPATIBILITY TESTS USED FOR?

Legislation regulating electromagnetic interference has become increasingly strict over the years, both to prevent direct risks to human health due to exposure to electromagnetic sources, both to minimize risk of malfunction due to electromagnetic interference. For example, the electromagnetic compatibility requirement for vehicles must be met by all manufacturers in order to obtain type approval for a car. As an accredited and recognized certification body, TÜV Italia (part of the TÜV SUD group) assists car (and other) manufacturers in both validation testing andelectromagnetic compatibility approval required by EU Regulation 2018/858. The purpose of electromagnetic compatibility tests for cars is therefore to verify the safety relating to immunity to electromagnetic fields and the levels of electromagnetic emission allowed.

20 TIMES MORE ELECTRONIC UNITS ON NEW CARS

THE automotive electromagnetic compatibility and immunity tests they have become increasingly important for homologation as the number of electronic control units on board increases. A recent new car has a 20 times greater number of control units compared to a car from a few years ago. “To give an example, when cars had a much more basic electrical system, compliance with the legislative requirement was more immediate and simpler”explains Pietro Vergani. “Once the power, ignition and lighting system and the surrounding systems were checked, it became very easy to be able to assess this aspect. Today also safety and security management electromagnetic compatibility has reached very high levels and this is a fairly critical test for Builders”.

THE TÜV ITALIA LABORATORY FOR ELECTROMAGNETIC COMPATIBILITY

There electromagnetic compatibility of new carsas the electrical safety and general safety of the vehicle, are requirements for which I Builders vehicles they share there responsibility with suppliers for technical qualification and certification purposes. Component manufacturers and car manufacturers turn to TÜV Italia to check the electromagnetic immunity of systems (for example an inverter for electric cars by simulating its real operation on the car), and to Vehicles. The place where the indoor tests are carried out is the EMC laboratory of the TÜV Italia Center in Volpiano. There is a large semi-anechoic chamber here (“semi” because the floor is not covered like the walls to bounce electromagnetic waves, but has passive rollers to simulate the operation of vehicles for testing at a distance of up to up to 10 meters from the units subjected to EMC tests). Different types of electromagnetic tests are carried out in the semi-anechoic chamber of the EMC TÜV Italia laboratory:

• immunityto assess whether the car or system under test is disturbed by an external electromagnetic radiation field;
• issueto assess the level of electromagnetic radiation emitted in normal operation to the exterior;

Both EMC tests can be performed to assess conducted emission and immunity 9 kHz to 110 MHz (i.e. via an electric cable, for example via the high voltage cables of electric cars) and beamed from 10 kHz to 26 GHz, which propagate in the test environment. In addition, it is also possible to perform radio frequency tests on RF units (such as wi-fi, bluetooth, etc.)

HOW ARE ELECTROMAGNETIC COMPATIBILITY TESTS DONE

As for the mandatory technical tests for homologation, also the car’s electromagnetic compatibility requirement it is assessed by checking the technical configuration of the vehicle which is always tested in fully optional configurationtherefore with all the control units provided by the Manufacturer. “The criterion with which the control units to be tested for electromagnetic compatibility are defined is that of security. For example, an electronic control unit which controls the ABS function must certainly meet higher validation criteria than a control unit which manages the electric window”. To assess the electromagnetic compatibility of a new car to be homologated as pre-production prototypethey can serve up to 2 days of trials. When, on the contrary, the technical service of TÜV Italia assists a Manufacturer in the development phase of a new modelvalidation tests may require up to 30 days for each electronic unit on board the vehicle, also involving dozens of different samples. In this case, however, more severe test conditions are also taken into account in relation to the minimum safety criteria established by EU Regulation No. 10 for electromagnetic compatibility. “A car has electrical components that may be more critical than others at the validation level, while at the homologation level the minimum requirement is cross-cutting and is the same for all systems or components”.

ELECTROMAGNETIC COMPATIBILITY OF ELECTRIC CARS AND ICE: WHAT IS THE DIFFERENCE

What has changed in recent years regarding the electromagnetic compatibility of cars with lithium batteries? “Over time, even the legislation itself – the UN ECE R10 regulation – has been updated several times to keep up with electric vehicles. One of the most significant tests for electric vehicle manufacturers it is precisely the electromagnetic compatibility when charging of the lithium battery, which is added to the electromagnetic compatibility tests carried out on traditional vehicles. Based on the manufacturer’s charging solution, we can carry out all tests at the TÜV Italia laboratory in Volpiano or at the TÜV SUD laboratories in Germany for more specific solutions, for example with Fast Charger. In the specific case of electric cars, however, there is no differentiation for the remaining evidence as to whether a high voltage battery, traction motor or wiper motor is occurring.”.

If you wonder why on a lithium battery separate from the car cannot be evaluated for electromagnetic compatibilityhere is the explanation. “A battery cell alone has no sensitivity to electromagnetic fields, so if we unpack a battery, the cell alone is not homologous because it has no verifiable structure from the point of view of the electromagnetic field. The same goes for cell modules, because until there are electronics to analyze and connect them and determine their energy level and current flows, it is not verifiable d an EMC point of view. Thus, in the case of vehicle traction batteries, the smallest unit that can occur is the subgroup with BMSwhich is normally the management unit of a set of cells or modules against which electromagnetic compatibility can be assessed”.